<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>压缩图片</title>
  <style>
  h3{ text-align: center; }
  #progress { height: 20px; width: 500px; margin: 10px 0; border: 1px solid gold; position: relative; }
  #progress .progress-item { height: 100%; position: absolute; left: 0; top: 0; background: chartreuse;  transition: width .3s linear; }
  .imgdiv{ width: 400px; text-align: center; display: none; }
  .imgdiv img{ width: 100%; }
  </style>
</head>
<body>
  <h1>上传文件</h1>
  <!-- <img src="/images/psc.jpg"/>  -->
  <input type="file" id="file" accept="image/*" multiple>
  <div style="margin:5px 0;">上传进度:</div>
  <div id="progress">
    <div class="progress-item"></div>
  </div>
  <p class="status"></p>
  <div class="imgdiv">
    <img src="" alt="" class="imgbox">
  </div>
  <div class="bbt">
    <button class="btn" style="display:none;">压缩</button>
  </div>
  <script>
  document
    .querySelector('#file')
    .addEventListener('change', function() {
      // File 对象  
      // es6 以前 是不可以的， 文件属于系统
      // 上传到服务器端处理
      // html5  File 对象 文件能力 上传到服务器前 文件的大小， 
      var file = this.files[0];
      // console.log(file, '------------');
      var formdata = new FormData(); // 表单数据
      formdata.append("file", file);
      const xhr = new XMLHttpRequest();
      xhr.open("post", "http://localhost:6300/uploadPic/")
      xhr.onreadystatechange = function() {
        if (xhr.readyState == 4 && xhr.status == 200) {
          document.querySelector('.btn').style.display = 'block';
          document.querySelector('.status').style.display = 'block';
          document.querySelector('.status').innerHTML = xhr.responseText;
        }
      }
      xhr.upload.onprogress = function(event) {
        if (event.lengthComputable) {
          let percent = event.loaded / event.total * 100;
          document
            .querySelector('#progress .progress-item')
            .style
            .width = percent + '%';
        }
      }
      xhr.send(formdata);
    })
  document
    .querySelector('.btn')
    .addEventListener('click', function() {
      document.querySelector('.status').innerText = '等待中...';
      var xhr = new XMLHttpRequest();
      xhr.open('get', 'http://localhost:6300/zipimg/');
      xhr.send();
      xhr.onreadystatechange = function()  {
        if (xhr.readyState == 4 && xhr.status == 200) {
          
        }
      }
    })
  </script>
</body>
</html>
